Micropunches are used in fabrication processes to form small holes, usually in environments requiring high precision. Parts or components of systems having high precision requirements rely upon the alignment and concentricity of the holes formed by these micropunches. If the holes are misaligned or have high concentricity errors, the system using those parts may fail.
Generally, a grind process forms the tip of the micropunch using a slow speed spindle and a collet. Sources of error in the process include temperature fluctuations in the spindle oil, misalignment of the spindle body in the collet, and component wear in some of the spindle components. In addition, the current spindle construction has several components having tight tolerances. As a result, the process builds the parts for each spindle together and parts do not exchange well between spindles. Replacement of worn parts becomes complicated and generally requires manufacture using instruments accurate enough to ensure proper alignment of the replacement part.
The sources of error may result in excessive concentricity error between the outer diameter of the punch body and the outer diameter of its ground punch tip. These errors may cause the tip to form a hole that is not properly aligned and/or not truly circular in a component part of a larger system. In some systems, this issue can cause yield losses up to 30%. These losses result in more material costs for manufacture of the components requiring highly precise apertures, raising the cost of the component and in turn of the whole system. Further, the errors can lead to system failures in the overall system.